1. Field of the Invention
The present invention relates generally to a system for diagnosing a malfunction within a machine, and more specifically to the investigation or analysis of a problem in a subsystem associated with an electrophotographic machine.
2. Description of the Prior Art
It is a generally known practice to utilize component exercising routines and other diagnostic functions within reprographic and printing systems to aid in the troubleshooting of such systems. For example, U.S. Pat. No. 4,882,778 to Hosaka et al. discloses an electronic load drive control apparatus with intelligent registers and a microprocessor which can execute control under predetermined conditions. The apparatus is simplified by a control unit, a program design and structure which utilizes an intelligent microcontroller. The microcontroller transmits information by an interrupt procedure to a microcomputer only when a control tolerance is reached. The microcomputer performs tasks and is capable of increasing the number of systems to be controlled.
U.S. Pat. No. 4,884,103 to Yamada discloses a programmed control device which is capable of connecting an external memory to a microcomputer. The control device and the external memory are then utilized to alter the main routine which is then usable instead of the unaltered main routine. Subsequently, the altered main routine may be used to operate the machine in conjunction with the external device, in accordance with the specifications and function of the external device.
However, what is not disclosed in the cited references is the ability to troubleshoot or diagnose problems in add-on or peripheral subsystems which may have been subsequently integrated with the base machine. For example, the add-on sorter subsystem disclosed by Yamada (U.S. Pat. No. 4,884,103), does not teach the use of the external memory for any diagnostic functionality. Moreover, the approach disclosed by Yamada would require the external subsystem to incorporate additional memory to alter the main routine of the base system. In addition, a full bus structure would need to be available for connection with the add-on system in order to provide memory access for the base system.
It is therefore an object of the present invention to provide a base machine with means for exercising the diagnostic functionality of a peripheral device or subsystem. It is a further object of the present invention, that the base machine will require no prior knowledge of the diagnostic functionality of the subsystem in order to provide an interface to that diagnostic functionality. It is yet another object of the present invention to utilize a common interface for the communication of diagnostic information between the base machine and all peripheral devices. It is a final object of the present invention to provide a common diagnostic user interface for any peripheral or add-on subsystem integrated with the base machine so as to enhance the serviceability of the entire system.
Further advantages of the present invention will become apparent as the following description proceeds and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.